This invention relates to a method for resin activation in pipeline repair.
A method presently used for repairing pipelines includes the use of a liner tube having a felt layer upon its inside and having a protective layer made of polymer or other plastic material on its outside. Resin is inserted into the liner tube for the repair process so as to impregnate all of the felt material within the inside of the liner tube with the resin. During this process a catalyst is also applied so as to activate the resin and cause it to begin its curing and hardening.
The liner tube is then inverted into the pipeline for repair so that the inner impregnated felt layer is inverted from the inside of the tube to the outside. The catalyst causes the resin to continue to harden, and when the resin hardens in place the felt layer provides a protective inner coat for the pipeline to be repaired.
One difficulty encountered with the present method is that the catalyst must be applied to the resin at the time that the resin is inserted into the interior of the tube and before transporting the tube to the repair site. Once the catalyst is applied to the resin, the resin begins curing and time is of the essence in order to get the liner tube in place within the pipeline to be repaired.
One method for slowing the curing of the resin is to refrigerate the liner tube until such time as it is inverted into the pipeline to be repaired. However, vehicles for refrigerating the liner tubes are expensive.
Other systems use a scaffolding to create a head of water at the repair site for inverting the liner and activating the cooled catalyst and resin. The water is circulated and heated by use of a boiler. The process of heating the water must be controlled and it takes a fair amount of time. Once the water reaches its peak temperature, that temperature must be held for a specified period of time. Then the water temperature must be cooled down in a controlled manner as well and that also takes considerable time.
As a result, many of the presently used systems for repairing pipeline take considerable amount of time. With current systems, an experienced crew can repair a pipeline between two manholes in approximately one day. Some highly skilled crews may be able to repair the pipeline between two sets of manholes in one day.
Therefore, a primary object of the present invention is the provision of an improved method for resin activation in pipeline repair.
A further object of the present invention is the provision of a method for pipeline repair which permits the resin to be placed in the liner tube in an inactivated state and permits the activation of the liner tube while it is within the pipeline to be repaired.
A further object of the present invention is the provision of a method for pipeline repair which permits the liner tube to be transported with the resin impregnated therein but without a catalyst applied.
A further object of the present invention is the provision of a method for pipeline repair utilizing a resin impregnated liner tube which can be transported without a refrigerated truck.
A further object of the present invention is the provision of a new system that will be more cost-effective than prior art systems.
A further object of the present invention is the provision of a method for resin activation in pipeline repair that permits any length of liner tube to be installed because the liner is activated only during the installation process.
The foregoing objects may be achieved by a method for repairing a pipeline which includes impregnating a liner material capable of absorbing a fluid with a fluid uncured and unhardened resin requiring a catalyst for activation to cure and harden. The method includes inserting the impregnated liner within the pipeline to be repaired and applying a catalyst to the impregnated liner while the liner is within the pipeline. The resin is then allowed to cure and harden to form a repaired surface for the interior of the pipeline.
According to one feature of the invention the liner tube comprises an outer layer and an inner layer with the inner layer being capable of absorbing a fluid. The impregnating step comprises introducing the resin into the interior of the tube. The tube is then inverted into the pipeline so that the inner layer is inverted to the outside of the tube and the outer layer is inverted to the inside of the tube.
According to another feature of the invention the catalyst is applied to the inner layer during the inverting process.
According to another feature of the invention the applying of the catalyst is done by spraying the catalyst onto the impregnated layer.
According to another feature of the invention the catalyst is applied within the pipeline.
The preferred method of the present invention is to apply the catalyst to the liner after the liner is within the pipeline. Alternatively the catalyst could be applied immediately before insertion into the pipeline. Also, a catalyst which only partially activates the resin could be applied before transport of the liner, with an additional catalyst being applied inside the pipe for final activation.
The present invention contemplates repair of all kinds of pipelines including, but not limited to, mainline sewer pipelines and lateral sewer pipelines. In the repair of lateral sewer pipelines the lateral liner tube is inverted from the main sewer pipeline into the lateral pipeline. Using a flexible rod push camera and a spray hose the catalyst is then applied to the resin impregnated lateral liner tube as it is being inverted into the lateral pipeline.
Another method for applying the catalyst to the liner tube while the liner tube is within the pipeline is to use two liner tubes, each of which has a resin absorbing inner layer and an outer layer that is smooth. The inner layer of first liner tube is impregnated with resin, but no catalyst. It is pulled into place within the pipeline with the impregnated inner layer inside the first liner tube. Then a second similar liner tube is impregnated with catalyst in its inner layer. The second liner tube is then inverted into the first liner tube so as to place the catalyst impregnated layer outside the second liner tube. This places the inner resin impregnated layer of the first tube in contact with the outwardly presented catalyst impregnated layer of the second tube, thereby activating the resin for curing. In this arrangement the first liner tube has its smooth surface facing outwardly and the second liner tube has its smooth surface facing inwardly.